P1335: SECONDARY MALIGNANCIES AFTER AUTOLOGOUS STEM CELL TRANSPLANTATION. SINGLE HOSPITAL EXPERIENCE.
Authors: A. Dorado López, M. Calviño Suárez, E. Lavilla Rubira, P. Sar Fuentes, J. A. Arias Sampedro, L. Lopez Gonzalez, M. J. Sánchez Sánchez, M. Varela Pérez
Journal: HemaSphere (2022)

Background: Autologous stem cell transplantation (ASCT) has a key role in the treatment of haematological malignancies, improving results and survival outcomes. Acute toxicity is well known and support therapy has improved over the years, with an overall procedure-related mortality currently being at 2-3%. However, there are long-term complications with high morbidity and mortality, such as secondary neoplasms, which limit the benefit of the procedure. The reported incidence ranges around 9-17% at 15 years after transplantation and they are responsible for 5-10% of late deaths. Aims: The main objective was to estimate the incidence and identify the risk factors related to second malignancies. Methods: We submit a retrospective study of 242 patients who underwent a total of 269 ASCT in our Institution over a period of 24 years (1995-2019). Multiple variables were collected from a clinical care database and statistically analysed using IBMSPSS-Stadistic-2019 and the proper comparative methods. Results: Of all the variables collected, it is worth mentioning the following: median age 56 (range 16-73), female (52.5%), diagnosis [LPDs (50.8%), MM (35.5%), AL (8.7%), other (4.8%)], >1 previous line of chemotherapy (44.2%) and second transplant (16%). The overall mortality (OM) at 2, 5 and 10 years was 21.5, 29.3 and 38% respectively, with a corresponding non-relapse OM of 10.3, 13.6 and 16.7%. Fifteen (7.2%) out of the 209 patients who were alive after 6 months from the transplant, developed a secondary cancer after transplantation: 11 solid neoplasms [oral (1), urologic (1), digestive (4), lung (3), breast (2)] and 4 hematologic [acute myeloid leukaemia (2), acute lymphoid leukaemia (1) and T lymphoma (1)] with the characteristics set out in Table 1. Additional risk factors (such as smoking and/or alcoholism) unrelated to the hematologic malignancy or previous therapies were identified in only 3 patients. The latency period from transplantation to onset of the malignancy was 8 years (range 3-13), a period that is shortened by half in the case of acute leukaemia (median 4 years, range 3-5). More than half of these patients (n=8; 53.3%) died as a direct cause of the second neoplasm, within a period ranging from 1-48 months with a median of 3 months. Therefore, it becomes the 2nd cause of death at 2- and 5-years following relapse of the underlying disease and the first cause at 10 years after transplantation. No differences were observed between patients with or without secondary neoplasm (Figure 1) in terms of overall survival neither according to the type of cancer. Data’s statistical univariant comparison (including age, sex, diagnosis, previous therapies, PH mobilization, conditioning regimen, radiotherapy...) identified only the additional execution of allogeneic transplantation (p value 0.001) as significantly associated with the development of the neoplasia. Image:Summary/Conclusion: The study verifies the incidence and morbidity and mortality associated with the development of secondary neoplasms and highlights the need for systematic follow-up of the long-term survivor in order to identify this complication as soon as possible. This is a complex process that requires the joint participation of a multidisciplinary team and the patient involvement in order to realize the risks still present many years after ASCT regardless the underlying disease’s remission. Given the heterogeneous population and the study’s retrospective nature we have faced some limitations, hence it is important to continue exploring this situation for a better understanding.